The US and Japan take notably different approaches.

The crisis at Japan's Fukushima site highlighted how three distinct sets of risks can interact: operator error, equipment and facilities failures, and siting near geological risks. We tend to think of that last one as a static risk—once a site is built, the hazards are more or less built in. But Fukushima demonstrated otherwise. Even as further studies clarified the earthquake and tsunami risk at the site, nothing was done to incorporate the new geological knowledge into safety evaluations, so no changes were made to the plants.

A short article in the American Geophysical Union's journal EOS looks at how Japan is responding to the revelations that are coming out of Fukushima, and it compares that response to the regulatory situation in the US. The most obvious response has been the shutdown and safety review that took all of Japan's reactors offline; for most of them, the reviews are still in progress.

There was a legislative response as well. The agency responsible for the plants, which has been accused of suffering from regulatory capture, was reorganized. In addition, new safety rules were put in place and are helping govern the restart. The EOS paper looks at the experience with the Tsuruga Nuclear Power Plant, which would be the oldest operational facility in Japan if given the green light to restart.

Tsuruga is situated on the coast in a steep valley that faces a narrow bay. A high ridge separates it from the Sea of Japan, which is the opposite coast from the faults most likely to generate a large tsunami. That's the good news. The bad news is that the valley and bay are formed by a fault that extends north-south for at least 10 km (its full extent is unmapped). The foundations of one of the reactors are less than 200 m from the main fault, and a smaller side fault extends directly underneath reactor 2.

When Tsuruga was built in the 1970s, these faults were considered inactive. But further research has shown that the main fault (Urasoko) has shifted a number of times over the past 120,000 years; current maps of Japanese faults call Urasoko either "active" or "possibly active." That bit of knowledge has triggered an extensive safety review.

To understand the risk, workers cut trenches across both faults on the site and used changes in the sediment to date earthquakes. (For example, the surface sediment deposits should be uninterrupted until the layers deposited just before the last major earthquake.) These trenches showed that the smaller faults closest to the rectors had been inactive for at least 120,000 years and were not triggered when the Urasoko fault shifted. The same work built a careful chronology of events at the main Urasoko fault, which can then be incorporated into the safety assessment.

The authors compare that assessment with how things have worked in the US and appear to suggest that a simple determination that a fault is "active" or "inactive" probably isn't the best way to go about things. They compare that process to the one under which California's Diablo Canyon power plant was licensed, which required an ongoing assessment of seismic risks. Plant operators have thus established a Long Term Seismic Program that updates safety considerations based on current research and models. In an example given in the article, the risk analysis data was updated significantly in the wake of 1989's Loma Prieta earthquake near Santa Cruz, CA.

Obviously, neither of these approaches can guarantee safety; the other two factors mentioned above (equipment and operators) can combine to turn a non-critical event into a disaster. But the report does a nice job of explaining how geological risks often don't provide a binary "safe" or "unsafe" distinction.

I feel that the headline and article don't match, based off the headline I seem to be missing half an article.

Also, I say decommission the worst of these reactors, then fill everything with colored gel. When the inevitable earthquakes finally hit you can find where the points of failure are without nuclear waste all over the place.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Um, who the hell thought setting up a nuke reactor in Diablo Canyon was a good idea?!

Your question brings up a more fundamental one -- why is it necessary to build reactors near faults at all?Is it that there are so many fault lines it's hard to find a place that doesn't have one?Are there just so few sites that are suitable for a reactor that being near a fault line can't be a disqualifying issue?Or is it the case that you can't serve a city that is near a fault line without the reactor being near that line as well?

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

Um, who the hell thought setting up a nuke reactor in Diablo Canyon was a good idea?!

They didn’t know there was a fault within a mile until late in design, so they revised the design to accommodate the accelerations. It should be fine, imo – I’ve seen the shake table testing of components that go into nuclear power plants to prove they’ll still work afterward, and I’m comfortable that it’s adequate. What’s harder to design for are tsunamis and anything that involves a lot of movement, like landslides and liquefaction – i.e. soil failure. As far as I know, those shouldn’t be issues at Diablo Canyon.

Being near a fault means you’ll experience the earthquake more as a single, large jolt. You just need strength for that – brute-force design is appropriate. It’s simpler (imo) than designing for what Fukushima experienced, a lower-acceleration event with many cycles, typical of earthquakes at subduction zones. In that situation, low-cycle fatigue becomes a challenge.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

You'd think so, but the capacity of a reactor to cause damage when it fails makes it a polarizing subject.

Um, who the hell thought setting up a nuke reactor in Diablo Canyon was a good idea?!

They didn’t know there was a fault within a mile until late in design, so they revised the design to accommodate the accelerations. It should be fine, imo – I’ve seen the shake table testing of components that go into nuclear power plants to prove they’ll still work afterward, and I’m comfortable that it’s adequate. What’s harder to design for are tsunamis and anything that involves a lot of movement, like landslides and liquefaction – i.e. soil failure. As far as I know, those shouldn’t be issues at Diablo Canyon.

Being near a fault means you’ll experience the earthquake more as a single, large jolt. You just need strength for that – brute-force design is appropriate. It’s simpler (imo) than designing for what Fukushima experienced, a lower-acceleration event with many cycles, typical of earthquakes at subduction zones. In that situation, low-cycle fatigue becomes a challenge.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

In one of the biggest earthquakes in world history, there was no significant earthquake damage to any Japanese nuke. The damage to the Daichi plant was caused by a corrupt regulator refusing to force irresponsible Tepco management to spend a few $millions to upgrade backup systems to allow for a once in 50 year or so Tsunami.event. Apparently there are other corruption related safety hazards now being corrected around the country.

There is no significant earthquake risk to US nuke plants. However the hundred or more unregulated uninsured, ready to blow US Bhopal type plants, are another story altogether.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

You'd think so, but the capacity of a reactor to cause damage when it fails makes it a polarizing subject.

It's a very charged issue, to be sure. Nuclear power has a lot of positives AND negatives.

Um, who the hell thought setting up a nuke reactor in Diablo Canyon was a good idea?!

Your question brings up a more fundamental one -- why is it necessary to build reactors near faults at all?Is it that there are so many fault lines it's hard to find a place that doesn't have one?Are there just so few sites that are suitable for a reactor that being near a fault line can't be a disqualifying issue?Or is it the case that you can't serve a city that is near a fault line without the reactor being near that line as well?

There are geologic faults of some kind pretty much everywhere that don't necessarily pose any significant risk. For example, in the eastern US the Appalachian region is criss-crossed with ancient inactive faults stemming from the time that it was a plate boundary.

As an aside, a photo of current construction on a nuclear power plant in the USA:

In one of the biggest earthquakes in world history, there was no significant earthquake damage to any Japanese nuke. The damage to the Daichi plant was caused by a corrupt regulator refusing to force irresponsible Tepco management to spend a few $millions to upgrade backup systems to allow for a once in 50 year or so Tsunami.event. Apparently there are other corruption related safety hazards now being corrected around the country.

There is no significant earthquake risk to US nuke plants. However the hundred or more unregulated uninsured, ready to blow US Bhopal type plants, are another story altogether.

As an engineer I am constantly and consistently appalled at the complete inability of my colleagues to understand even the most fundamental principles of physics. Academic standards in this discipline need to be severely overhauled and ongoing testing for practicing engineers is long overdue.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

You'd think so, but the capacity of a reactor to cause damage when it fails makes it a polarizing subject.

It's a very charged issue, to be sure. Nuclear power has a lot of positives AND negatives.

That's right. The alternating currents of public opinion can be quite shocking, potentially leading to meltdowns in communicating the actual facts about the risks of nucler energy.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

You'd think so, but the capacity of a reactor to cause damage when it fails makes it a polarizing subject.

It's a very charged issue, to be sure. Nuclear power has a lot of positives AND negatives.

That's right. The alternating currents of public opinion can be quite shocking, potentially leading to meltdowns in communicating the actual facts about the risks of nuclear energy.

Well, if not full meltdowns, then partial meltdowns, accompanied by the release of a lot of hot air from the energized populace.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

Um, who the hell thought setting up a nuke reactor in Diablo Canyon was a good idea?!

They didn’t know there was a fault within a mile until late in design, so they revised the design to accommodate the accelerations. It should be fine, imo – I’ve seen the shake table testing of components that go into nuclear power plants to prove they’ll still work afterward, and I’m comfortable that it’s adequate. What’s harder to design for are tsunamis and anything that involves a lot of movement, like landslides and liquefaction – i.e. soil failure. As far as I know, those shouldn’t be issues at Diablo Canyon.

Being near a fault means you’ll experience the earthquake more as a single, large jolt. You just need strength for that – brute-force design is appropriate. It’s simpler (imo) than designing for what Fukushima experienced, a lower-acceleration event with many cycles, typical of earthquakes at subduction zones. In that situation, low-cycle fatigue becomes a challenge.

Overhead capacitors to one oh five percent. Uh, it's probably not a problem, probably, but I'm showing a small discrepancy in... well, no, it's well within acceptable bounds again. Sustaining sequence.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

The chance of an earthquake causing core damage at Indian Point 3 is estimated at 1 in 10,000 each year. Under NRC guidelines, that's right on the verge of requiring "immediate concern regarding adequate protection" of the public. The two reactors at Indian Point generate up to one-third of the electricity for New York City. The second reactor, Indian Point 2, doesn't rate as risky, with 1 chance in 30,303 each year.

Japan has a much bigger issue. They still operate a dual Hz system. Part of the country is 50Hz and the other half is 60Hz. What this meant was when the plant was flooded and the generator was swamped they had very limited options for routing the power to get the cooling pumps started again.

Yeah, that really put the Hertz on them.

You'd think the frequency of a problem like that these days would be almost nil.

Nuclear fears are an interesting psychological phenomenon. You have a better chance of dying from just about every other type of power source and dozens of other common daily activities.

That's just dying though. The risks of nuclear power also include other risks that, although less serious than death, are also more common. For example, the risk of being bitten by a radioactive spider or absorbing massive amounts of gamma radiation.

Like ws3 mentioned, I meant inland reservoirs. It doesn't have to be a huge ship. Just the general idea of decoupling the building from the foundation by using a liquid buffer.

Thing is, for the most part building to account for earthquakes is pretty far along in Japan, and while the liquid buffer might be useful, the risks of putting them on a floating surface are probably more significant (things like capsizing) than putting them on solid ground or burying them sufficiently deeply that seismic forces wouldn't really impact them.

There's a reason, for example, that Tokyo is burying all its major infrastructure.